Skin treatment with electromagnetic or mechanical waveform energy

ABSTRACT

A hand held device generates a predetermined number of pulses of electromagnetic radiation having a predetermined electromagnetic spectrum, a predetermined duration, a predetermined inter-pulse interval, and a predetermined total energy. The pulse sequence is delivered to a skin surface to reduce or eliminate Xray or ultraviolet radiation damage to the skin surface.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of Application No. 10/647,948 filedAug. 26, 2003, now U.S. Pat. No. 7,931,028.

BACKGROUND OF THE INVENTION

This invention relates generally to a process for treating the skin withlight, i.e., electromagnetic radiation in the visible and infraredportions of the electromagnetic spectrum.

Exposure to Xrays and/or Ultraviolet (UV) light can produce damage toskin and body tissues. This damage can produce immediate, short term orlong term changes. These changes can be temporary or permanent. Benignskin changes can range from temporary irritation such as seen inradiation burns or sun burns, or can be more delayed such as radiationdermatitis or chronic sun damage (poikiloderma).

Malignant changes can include pre-cancerous lesions such as ActinicKeratoses or leukoplakia or cancerous changes such as squamous cellcarcinoma, or basal cell carcinoma, or malignant melanoma. These changesfrequently occur in the exposed tissue, but they also occur innon-exposed areas. Among the three most common skin cancers (basal cellcarcinoma, squamous cell carcinoma, and melanoma), melanoma has beenreported to be the most common in non-sun exposed areas, while it is theleast common overall of the three skin cancers.

Procedures for preventing damage from Xrays and UV light include:avoiding exposure, and using mechanical or chemical screens to block theenergy waves, as well as oral or topical products such as antioxidants,or retinoids to prevent or repair the damage before or after damage hasoccurred. Topical or oral chemotherapy has also been used to reverse orprevent progressive damage, precancerous or cancerous changes. Surgerywith scalpels, surgical instruments or with cutting lasers has been usedto remove or ameliorate damaged, precancerous or cancerous areas.

Xrays have also been used to selectively target cancers. By deliveringXray energy to specific sites, those sites may selectively be damaged ordestroyed. Even though the long-term side effects may include scarringand/or precancer and/or cancer, the beneficial shorter term clearing ofthe undesirable tissue may outweigh the longer-term risks. Thesebenefits are especially valuable in the elderly patient.

Light in the visible and/or infrared spectrum has been applied to skinsurfaces for purposes of treating blood vessels, pigmentary changes, andirregular surface topography of the skin (elevations and/or depressionsand/or scarring). The light is applied either alone or in combinationwith photosensitizing agents and specifically targets chromophores suchas the hemoglobin in blood, melanin in skin, or porphyrinphotosensitizers that accumulate in target tissue.

Photodynamic therapy (also called PDT, photoradiation therapy,phototherapy, or photochemotherapy) is a treatment for some types ofcancer. It is based on the discovery that certain chemicals known asphotosensitizing agents can kill one-celled organisms when the organismsare exposed to a particular type of light. PDT destroys cancer cellsthrough the use of light in combination with a photosensitizing agent.

In PDT, the photosensitizing agent is injected into the bloodstream andabsorbed by cells all over the body. Alternatively, the photosensitizingagent may be applied topically for treating precancerous and cancerousskin. The agent accumulates more in cancer cells than it does in normalcells. When the treated cancer cells are exposed to light, thephotosensitizing agent absorbs the light and produces an active form ofoxygen that destroys the treated cancer cells. Light exposure must betimed carefully so that it occurs when most of the photosensitizingagent has left healthy cells but is still present in the cancer cells.The light may have a wavelength between 650-800 nm for tissuepenetration purposes.

The photosensitizer used in photodynamic therapy should be partiallyhydrophilic for injection and delivery purposes and partially lipophilicfor cell uptake purposes. Porphyrins are typically used asphotosensitizers. Polarity and partition coefficient of these compoundscan be altered by attaching polar residues (such as amino acids, sugars,nucleosides) onto the fundamentally hydrophobic porphyrin ring.

In December 1995, the U.S. Food and Drug Administration (FDA) approved aphotosensitizing agent called porfimer sodium, or Photofrin®, to relievesymptoms of esophageal cancer that is causing an obstruction and foresophageal cancer that cannot be satisfactorily treated with lasersalone. In January 1998, the FDA approved porfimer sodium for thetreatment of early nonsmall cell lung cancer in patients for whom theusual treatments for lung cancer are not appropriate. The NationalCancer Institute and other institutions are supporting clinical trials(research studies) to evaluate the use of photodynamic therapy forseveral types of cancer, including cancers of the bladder, brain,larynx, and oral cavity. Researchers are also looking at different laserlight types, photosensitizers that can be applied to the skin to treatsuperficial skin cancers, and new photosensitizing agents that mayincrease the effectiveness of PDT against cancers that are locatedfurther below the skin or inside an organ.

Researchers have investigated the effect of visible light treatments onsun-damaged skin. The investigation applied light in two periorbitaltreatments six weeks apart. In each session, the light had a wavelengthof 590-1200 nm and was applied in two pulses each of 4.5 msec duration,with an interpulse interval of 10 msec and a total applied energy of 42J/cm². The researchers found an increase in cancer-destroying enzymesMMP-I, MMP-II, TIMP-II, Caspase III. The investigation uncovered alocalized increased expression of protein in the fibroblasts after thetreatment. The researchers suggested that the application ofelectromagnetic radiation to sun-damaged skin might reduce the chancesof skin cancer formation and theorized that the light treatmentstimulates dermal fibroblasts to increases the production of matrixmetaloproteases, their inhibitors, and markers of apoptosis.

OBJECTS OF THE INVENTION

An object of the present invention is to provide a method for treatingskin to promote and/or protect the health of the skin and underlyingtissues.

It is a more specific object of the present invention to provide amethod for treating skin as a prophylactic measure.

An even more specific object of the present invention is to provide sucha treatment method that reduces or inhibits skin tissue damage thatmight otherwise accrue owing to Xray or ultraviolet light exposure.

It is further object of the present invention to provide such atreatment method that is safe for home use.

It is a related object of the invention to provide such a treatmentmethod that is easy to use.

A further related object of the present invention is to provide such atreatment method that can result in smooth healthy skin and underlyingtissue layers.

These and other objects of the present invention will be apparent fromthe drawings and descriptions herein. It is to be understood that eachobject of the invention is achieved by at least one embodiment of theinvention. It is not necessarily the case that any embodiment achievesall of the objects of the invention.

SUMMARY OF THE INVENTION

The present invention contemplates the use of electromagnetic energy toprevent, or treat damage from Xray or UV light. The light treatment of askin surface is effectuated in the absence of visually detecting anyXray or ultraviolet radiation damage to the skin surface. Thus, thepresent invention is directed to the preclinical treatment of skin as aprophylactic measure against potential Xray or ultraviolet radiationdamage.

Visible and/or infrared light energy applied to a skin surface pursuantto the present invention is absorbed by melanin in the epidermis andhemoglobin in the capillaries and blood vessels of the dermis. Theabsorption of light (visible and/or infrared) increases the localtemperature in the tissues containing the chromophores, such as theblood vessel cell walls and keratinocytes in the skin. The rise in heatof these structures above a certain level stimulates a healing responseand a release of growth factors and other tissue substances. This isdone without permanently damaging these structures.

The increase in the temperature of the target tissues is effectuated inaddition by energy transfer owing to light scattering. Energy transferin this case does not arise from light interaction with a chromophorebut rather by random light interaction with undetermined other molecularspecies.

The present invention further contemplates that the light application toa skin surface is undertaken in anticipation of, or during or shortlyafter, an exposure of the individual to the sun or other source of Xrayand ultraviolet radiation. If the application of light precedespotentially dangerous exposure, it is preferred, but not required, thatthe treatment is as close as possible to the time of exposure.Similarly, if the application of light occurs after potentiallydangerous exposure, the delay before skin treatment is preferably, butnot necessarily, minimized. The invention finds that intervals ofminutes or hours between light treatment and exposure are optimal. Theinvention recognizes, however, that benefits may be attained even if theintervals between the exposure and the light treatment are on the orderof days.

Nevertheless, where several treatment sessions are used, some or all ofthose treatments may be scheduled at times substantially removed fromthe time of exposure to Xray or UV radiation. For individuals who areexposed to the sun regularly, it is possible for the light treatments tobe done regularly as well. For instance, daily or weekly treatments maybe optimal for some individuals.

More specifically, the present invention contemplates delivering, to askin surface, visible light and/or infrared light with a wavelength ofabout 400 to about 1200 nm, in particular, either alone or incombination with sound waves, ultrasound waves and/or magnetic waves. Amethod pursuant to the present invention serves to prevent, reduce,improve, or clear the potential, immediate, chronic and/or long termchanges resulting from non-beneficial energy.

Selection of complementary energy settings which may offset thephysical, biochemical, or any negative change produced by theundesirable energy—will benefit the patient.

This beneficial energy may be delivered to any area—whether including orexcluding the original target area of the undesirable energy. Thisbeneficial energy may be delivered at any time—before, during, or afterthe undesired energy is delivered or in various combinations thereof.

Where an individual's skin is exposed to deleterious energy at a beachor a tanning salon, it is possible to deliver the prophylactic lightenergy to the individual's entire skin surface in a small chambercontaining the user. The user preferably wears goggles to protect theeyes and may stand in a small enclosed space—a light chamber—during theapplication of light to the entire skin surface. The light may beapplied via a contact device, as described specifically herein withreference to the drawings, and/or via a non-contact apparatus, asdiscussed below.

Beneficial energy may be delivered in varying combinations andstrengths. The protocols for delivering beneficial energy may bestandardized based on experience or may be individualized based onanalysis of specific exposures and changes induced or produced byundesirable energy exposures.

Means for delivering the desirable energy may include hand-held orlarger sized devices. These devices may be located in residential and/orcommercial, public and/or private, indoor and/or outdoor settings—andmay be used on a prescribed regimen or individualized regimen with orwithout known exposure to undesirable energy.

In accordance with another feature of the present invention, it ispossible to provide the skin with an exogenous chromophore that isabsorbed into essentially all the dermal or epidermal cells for purposesof enhancing light absorption. This option is particularly desirable forindividuals with skin of low natural melanin content. One suchchromophore is porphyrin, that may be applied topically, to facilitateselective absorption by the target skin tissues. It is noted thatmelanin or precursors of melanin are not generally absorbable into theskin. As indicated above, beneficial effects of light treatment may beachieved by a scattering mechanism instead of absorption, in which casean exogenous chromophore is not necessary.

A skin treatment method in accordance with the present inventioncomprises applying an effective amount of electromagnetic radiation to atarget skin surface to at least partially prevent, reverse, or inhibitdamage to the skin caused by exposure of the individual (and notnecessarily the target skin surface) to Xray or ultraviolet radiation,such as from the sun. The electromagnetic radiation is applied to theskin surface on at least one occasion prior to, during or after theexposure of the individual to Xray or ultraviolet radiation. It iscontemplated that the radiation is applied to the skin surface in theabsence of any visible Xray or ultraviolet radiation damage on the skinsurface. The radiation is applied as a prophylactic or preventativemeasure to obviate any possible Xray or ultraviolet radiation damagethat might otherwise occur because of exposure to the sun or othersource of Xray or UV radiation.

It is to be noted that the present invention contemplates in part thetreatment of skin areas that are not exposed directly to the sun orother source of Xray or UV radiation. Accordingly, skin surfaces thatare covered by clothing during an individual's exposure to the sun maybe subject to the light treatment of the present invention. Suchtreatment is based on the fact that melanomas are known to occur innon-exposed areas of an individual's skin. The mechanism for this is notknown and may possibly rest on a blood factor.

Pursuant to another feature of the present invention, the applying ofthe electromagnetic radiation includes (a) generating a predeterminednumber of pulses of electromagnetic radiation each having apredetermined electromagnetic spectrum, and (b) directing the pulses ofelectromagnetic radiation towards the skin surface of the individual,who is exposed to Xray or ultraviolet radiation. The pulses have atleast one pulse duration and a total energy all predetermined to reducedirect or indirect Xray or ultraviolet radiation damage to the tissuesof the skin surface. “Direct” radiation damage refers to skin areas thatare exposed to Xray or ultraviolet radiation, whereas “indirect”radiation damage refers to skin areas that are shielded, for instance,by clothing during exposure of the individual to Xray or ultravioletradiation.

Pursuant to more specific features of the present invention, the numberof pulses is greater than one, the pulses have an inter-pulse intervalbetween approximately 1 msec and 500 msec, the total energy is betweenapproximately 0.01 Joule and approximately 200 Joules of energy persquare centimeter of the skin surface, and the pulse duration is betweenabout 1 msec and 2 sec.

Even more specifically, the pulse duration is between about 1 msec and100 msec, whereas the total energy is between approximately 1 Joule andapproximately 90 Joules of energy per square centimeter of the skinsurface.

In one particular embodiment of the method in accordance with thepresent invention, the number of pulses is two, the pulse duration isabout 5.8 msec, the interpulse interval is approximately 20 msec, andthe total energy applied is between about 20 Joules per squarecentimeter of the skin surface and about 90 Joules per square centimeterof the skin surface.

In another particular embodiment of the method in accordance with thepresent invention, the number of pulses is one, the pulse duration isbetween about 18 msec and 25 msec, and the total energy applied isbetween about 20 Joules per square centimeter of the skin surface andabout 90 Joules per square centimeter of the skin surface.

Preferably, the electromagnetic radiation of the pulses is incoherentand wherein the spectrum includes wavelengths between about 400 nm and1200 nm. It is furthermore preferable to apply the light during anygiven treatment session in pulse packets that are separated by a periodthat is great in comparison to the interpulse duration(s) of the pulsepackets. This inter-packet period may be anywhere from one-tenth of asecond to several minutes. Where a hand treatment device is being used,it is convenient to treat an entire skin surface with a first pulsepacket during a first pass and then treat the same skin surface with asecond pulse packet during a second pass. Where a light chamber is used,the individual may wait as long as a few minutes between successivepulse packets, without incurring any fatigue or boredom.

The use of multiple passes enables each pulse packet to deliver asmaller amount of energy, thus lowering the intensity or the rate thatthe light energy is applied to the skin surface. Instead of 50Joules/cm² delivered in one pass, 20-25 Joules/cm² are delivered in eachof two passes. Further reduction in the applied energy to 1 Joule/cm² orless is possible, without adversely impacting the effectiveness of thetreatment, provided that the number of passes is increased to enablesufficient application of energy. This multiple pass treatment is notonly effective to treat the target skin surface but is safer and resultsin fewer side effects. There is a reduced risk of burning or irritation.The treated individual cannot even sense that the light treatment hasoccurred. The multiple pass method is particularly effective in treatingskin that is tanned or otherwise heavily pigmented. Further advantagesof using multiple passes include the manufacture of safer machines atless expense.

It is hypothesized that the effectiveness of multiple passes stems inpart from chemical reactions that are induced from the light appliedduring the first pass. It is possible that light absorbed by melanin,hemoglobin, and other lights-sensitive molecules causes a conformationalor chemical change in those molecules that renders the molecules morereceptive to additional light absorption, perhaps of light of differentwavelengths. Accordingly, broadband light treatment is desirable in theabsence of knowing exactly which wavelengths are absorbed at which timesby which molecules.

The present invention contemplates that the electromagnetic radiationmay applied to the skin surface in different treatment sessions onmultiple occasions each in conjunction with a respective exposure of theindividual to Xray or ultraviolet radiation. Thus, an individual mayapply the radiation to his or her skin prior to, during, and/or aftereach exposure of the individual to the sun. Where the individual has aregular and continuing exposure to Xray or ultraviolet radiation, theindividual may apply the electromagnetic energy to his or her skin witha periodicity corresponding to that of the individual's exposure.

Pursuant to the present invention, each application of theelectromagnetic radiation to the skin surface is effectuated within acertain interval of a respective exposure of the individual to Xray orultraviolet radiation. Preferably, but not necessarily, the applicationof electromagnetic radiation to a skin surface is within one day ortwenty-four hours of the exposure of the individual to Xray orultraviolet radiation. More preferably, the application ofelectromagnetic radiation to a skin surface is within twelve hours ofthe exposure of the individual to Xray or ultraviolet radiation. Mostpreferably, the application of electromagnetic radiation to a skinsurface is within one hour of the exposure of the individual to Xray orultraviolet radiation. These intervals apply regardless of whether theapplication of electromagnetic radiation to a skin surface is prior toor after the exposure of the individual to Xray or ultravioletradiation. In any event, the present invention contemplates theapplication of light in the visible and/or infrared spectrum to skinthat is visibly undamaged by Xray or UV radiation exposure, whethersolar or otherwise. The light treatment is therefore a preclinical orprophylactic method.

The electromagnetic radiation applied to the skin surface may have awavelength absorbable by an endogenous chromophore in tissues along theskin surface. The endogenous chromophore may be melanin and/orhemoglobin. In the case of melanin, the natural melanin content of theskin may be enhanced by topical application of a composition containing,for instance, porphyrin or other chromophore absorbable through theepidermis.

Where the applying of the electromagnetic radiation to the skin surfaceis carried out on multiple occasions or sessions, at least one of theoccasions may be further removed in time than at least another of theoccasions from the exposure of the individual to Xray or ultravioletradiation. This is particularly the case where the multiple applicationsof electromagnetic radiation are all before or all after the exposure toXray or ultraviolet radiation. Where there are but two applications ofelectromagnetic radiation, one before and one after the Xray or UVradiation exposure, those applications may possibly occur at the sametime interval before and after the exposure.

The occasions or sessions of electromagnetic radiation application maybe regularly spaced in time from one another, for instance, daily orweekly. Successive sessions are typically spaced by at least about ahalf hour from one another. Preferably, successive sessions are spacedby an inter-session interval of at least several hours.

In accordance with another feature of the present invention, the methodcomprises the transmission of ultrasound energy into biological tissuesalong the target skin surface prior to, during, after, or in lieu ofapplying the electromagnetic radiation to the skin surface.Alternatively or additionally, the method also comprises applying amagnetic field to biological tissues along the skin surface prior to,during, after or in lieu of the applying of the electromagneticradiation to the skin surface.

Accordingly, a skin treatment method in accordance with the presentinvention comprises applying an effective amount of mechanical pressurewaves to a skin surface to at least partially prevent, reverse, orinhibit damage to the skin caused by exposure to Xray or ultravioletradiation. The mechanical pressure waves are applied to the skin surfaceon at least one occasion prior to, during or after the exposure of theindividual to Xray or ultraviolet radiation. The application of themechanical pressure waves to the skin surface is effectuated in theabsence of any visible Xray or ultraviolet radiation damage to the skinsurface. The mechanical pressure waves may have a sonic or ultrasonicfrequency.

Concomitantly, a skin treatment method in accordance with the presentinvention comprises applying an effective amount of magnetic energy to askin surface to at least partially prevent, reverse, or inhibit damageto the skin caused by exposure to Xray or ultraviolet radiation. Themagnetic energy is applied to the skin surface on at least one occasionprior to, during or after the exposure of the individual to Xray orultraviolet radiation. The magnetic energy is applied to the skinsurface in the absence of any visible Xray or ultraviolet radiationdamage to the skin surface. The magnetic energy may be applied in theform of an alternating magnetic field. The frequency of fieldoscillation may be anywhere from several Hz to several million Hz.

A prophylactic skin treatment method particularly directed to thetreatment of ostensibly undamaged or preclinically damaged skinpreferably comprises, in accordance with the present invention, (i)generating a predetermined number of pulses of electromagnetic radiationeach having a predetermined electromagnetic spectrum, (ii) applying thepulses of electromagnetic radiation to an individual's skin surface, thepulses having at least one predetermined pulse duration, and apredetermined total energy, (iii) exposing the individual to Xray orultraviolet radiation, and (iv) at least in part owing to the applyingof the pulses to the skin surface, reducing or preventing damage to thetissues of the skin surface arising from the exposing of the individualto Xray or ultraviolet radiation. The electromagnetic spectrum mayinclude at least one wavelength absorbable by an endogenous chromophore(e.g., melanin and hemoglobin) in the person's skin tissues.

A device for skin treatment comprises, in accordance with the presentinvention, a hand-holdable casing, a generator of electromagneticradiation mounted to the casing, means on the casing for directingradiation from the generator to a skin surface, and an ancillary energygenerator mounted to the casing for producing another form of energy forapplication to the skin surface.

The ancillary energy generator may be an ultrasonic pressure wave deviceincluding an electromechanical transducer and an ultrasonic-frequencyelectrical wave generator.

Where the means for directing electromagnetic radiation to a skinsurface includes a flexible applicator member at least partiallyconformable to a topography of the skin surface, the ultrasonictransducer is in operative contact with the flexible member fortransmitting ultrasonic pressure waves to the skin surface through theflexible member. The flexible member may take the form of a fluid-filledpouch.

The ancillary energy generator may include an electromagnet for theapplication of a magnetic field to the skin tissues.

The pulse parameters, namely, the pulse number, the pulse duration(s),the inter-pulse interval(s), the total energy and the spectraldistribution(s), are selected in concert to reduce or prevent Xray-and/or UV-light-induced damage to the treated skin surface. Thisselection may be made in accordance with (1) a chromophore concentrationwithin the target skin tissues and/or (2) the expected amount(frequency, duration, intensity) of Xray and/or UV light exposure. Aconsumer device for the application of electromagnetic radiation pulsesin accordance with the present invention may be preprogrammed to selectthe pulse parameters in accordance with user input as to the darkness ofthe user's skin and the amount of exposure to the sun or other source ofXray and UV radiation. Alternatively, a light applicator device mayprovide for user selection of pulse parameters. The input of skin toneand exposure levels and/or the selection of pulse parameters may beeffectuated via separate actuators such as knobs or via a keyboard orkeypad. In the latter case, the user input or selection process may bedirected by prompts shown on a display under the control of amicroprocessor.

The electromagnetic radiation used in a skin treatment method inaccordance with the present invention may be incoherent and produced bya flashlamp or other source of incoherent electromagnetic radiation.Alternatively, the applied radiation may be coherent and produced by alaser source. In the former case the electromagnetic spectrum of thelight pulses is a band of wavelengths, while in the latter case, theelectromagnetic spectrum of a light pulse delivered at one time is asingle wavelength or a set of single wavelengths. In the former casefilters may be used to limit the band of transmitted wavelengths, whilein the latter case the laser source may be adjustable or tunable forproducing wavelengths of different frequencies. The light energy appliedmay include at least one wavelength absorbable by an endogenouschromophore in skin tissues such as melanin or hemoglobin.

In accordance with the present invention, a user determines the tone ormelanin content of a selected skin surface, as well as the quantity andnature of exposure to the sun or other source of Xray and UV radiation.The pulse parameters of the light application are then automatically orpartially automatically selected in accordance with the determined skintone and radiation exposure. Where the user is allowed to select pulseparameter values, there will be an automatically implemented limitationon the selection of parameter values so that the light energy appliedwill not be dangerous to the health of the target skin.

The method of the present invention contemplates a frequency of lighttreatment that is consistent with the frequency and intensity of theindividual's exposure to the sun or other source of dangerous radiation.For example, a user may apply the pulsed light energy daily where theindividual has daily sun exposure. Where the individual goes outdoorsonly once a week (for example, to shop), the user may apply the pulsedlight energy weekly.

Pursuant to the present method, light energy may be applied to anexposed or unexposed skin surface prior to the exposure of theindividual to Xray or ultraviolet radiation. If the individual fails toapply light prior to radiation exposure, he or she may apply the lightenergy after the exposure. For instance, if a user goes to the beachserendipitously, the user may apply light pulses in the evening, afterthe user returns to his or her place of abode.

The effect of light treatment in accordance with the present inventionwill depend in part on the individual's genetics as to skin color and onthe selected treatment parameters such as total energy, pulse rate,pulse duration, light spectrum, etc., as well as by the particular areaon the user's body. The effect of the light treatment will depend inpart on the quality and quantity of exposure to the sun or other sourceof potentially harmful radiation. In any given individual, the amountsof melanin and hemoglobin in facial; underarm, leg tissues, etc., vary.

The method of the present invention may be applied to facial skin, legskin, arm skin, neck and chest skin, etc., using hand held devices ofprior art designs, for instance, with a light source such as aflashlamp, a reflector, one or more lenses, and an application interfacesuch as a skin-contacting crystal. The crystal may function as a coolingelement. Alternatively, a separate cooling medium such as a gel may beapplied to the skin surface prior to the light application.

It is hypothesized that light administered in accordance with thepresent invention including wavelengths that are multiples of the200-400 nm wavelength range of ultraviolet radiation. It is consideredthat the prophylactic effect of light treatment is largely owing tothose wavelengths that bear a harmonic relationship to the wavelengthsof the damaging radiation. Thus, light at wavelengths of 800 nm, and1200 nm are particularly beneficial to obviating the adverse effects ofultraviolet light having a wavelength of 200 or 400 nm. Pursuant to thistheory, light is best administered over a range of wavelengths where theultraviolet radiation occurs in a range of wavelengths including 200-400nm.

Accordingly, the present invention contemplates the use of a hand helddevice for generating a predetermined number of pulses of light having apredetermined electromagnetic spectrum and for applying the pulses oflight to skin, the pulses having one or more predetermined durations,one or more predetermined inter-pulse intervals (if number of pulses isgreater than one), and a predetermined total energy. The device is usedto temporarily provide healing impetus to skin. Light pulses applied toa skin surface are expected to have an optimal prophylactic affect up toabout twenty-four hours after the application of the light pulses.However, light pulses applied more than twenty-four hours prior to sun(or other) exposure will still have a benefit, although reduced. Wherethe interval between a light application and a subsequent radiationexposure is more than twenty-four hours, it is recommended that at leastone other light application be carried out within twenty four hoursafter the exposure. Regular treatment of the skin with light pulses willhave a beneficial effect even if undertaken without attention to thefrequency, times, and nature of potentially harmful radiation exposure.Thus, light treatment may be used generally to promote skin health.

The light treatments may be performed without application of exogenouschromophores for light absorption purposes. Skin treatment is theneffectuated through light absorption solely by endogenous chromophoressuch as melanin and/or via light scattering in the epidermal, dermal andsubdermal tissues. Exogenous chromophores may be added for purposes ofenhancing the light absorption. This option is particularly appropriatefor persons of light skin tone. Porphyrin may be used as an endogenouschromophore, preferably applied via a topical cream or gel.

The inter-pulse interval (where the number of pulses is greater thanone) may, in different applications of the invention, be anywhere from 1millisecond to 2 seconds. Generally, the smaller the inter-pulseinterval, the greater the risk of damage to the skin. Thus, the smallerinter-pulse intervals should be used only in professional settings. Inhome-based embodiments of the invention, the inter-pulse interval of alight treatment is preferably greater than about 20 msec and morepreferably greater than 200 msec. An inter-pulse interval of such amagnitude reduces the chances of inadvertent damage to the epidermis.Preferably, the inter-pulse interval is between 200 msec and about 500msec. An inter-pulse interval of 300 msec is effective.

The total energy applied may be anywhere from 0.01 Joule per squarecentimeter of treated skin surface to about 200 J/cm². Generally, thehigher energies entail greater risk to skin integrity and should be usedonly by skilled professionals. For home use, the total energy appliedshould be lower, preferably between approximately 1 J/cm² andapproximately 100 J/cm² of the skin surface and more preferably betweenapproximately 5 J/cm² and approximately 90 J/cm² of the skin surface.The higher portion of this energy range is appropriate for persons oflight skin color. Where the skin color is on the dark side, the upperlimit of the total energy applied to a unit of skin surface should beless, for instance, approximately 20 J/cm².

Generally, it is contemplated that devices used in a method pursuant tothe present invention will require a selection of a maximum or totalenergy to be applied to a skin surface. This requirement typicallyentails some restriction on the user's freedom in selecting themagnitudes of other pulse parameters. In a simple device, the user maybe able to select only one pulse parameter, namely the total energy.Such a device might, for instance, have high, medium and low settings,alternatively designated as light skin, medium tone skin, and dark skinsettings. In a more complex device, setting of the total energy appliedby a pulse sequence will limit the range of options available to theuser in setting the other parameters. For instance, once the userselects the total energy and the pulse duration, the number of pulses isdetermined, provided that the rate of energy production or intensity isnot adjustable. If the intensity is adjustable, the user will have someleeway in selecting both the pulse duration and the number of pulses. Inthat case, the intensity may be automatically controlled by thelight-generating device so that the total energy does not exceed the setvalue.

The duration of the light bursts or pulses may be as little as 1millisecond or as great as two seconds. The shortest durations andhigher energies are recommended for professionally supervised lighttreatments only. For ordinary consumers or unskilled users, the pulseduration should be longer, preferably above approximately 5 msec andmore preferably between approximately 5 msec and approximately 30 msec.

Pursuant to one embodiment of the present invention, the light of thepulses is incoherent and the spectrum includes wavelengths between about400 nm and 1200 nm. Longer wavelengths are used for darker skin, fordeeper skins and deeper removal. In some embodiments of the invention,the spectrum of the pulses may be limited to wavelengths between about400 nm and 550 nm. These embodiments will require a more frequentapplication of the light energy to effectuate skin treatment.

The number of pulses in each pulse sequence or treatment session (asapplied to a given skin area) may be between one and ten, while thetotal duration of a pulse sequence ranges between 1 millisecond and 38seconds.

As indicated above, the present invention contemplates that someadjustment may be made by the user in the particular operationalparameters of the light application device. For instance, a simplehand-held device may have a plurality of settings, for instance, high,medium, and low (light skin, medium skin, dark skin), where one or moreof the operational parameters have different pre-established valuesdepending on the setting. Thus, high, medium, and low settings may varyin the number of applied pulses, the pulse duration, the inter-pulseinterval, and/or the total energy applied. A user could start with a lowsetting to see whether the skin is adversely affected in any way and ifnot, try the next higher setting. Usually, it is preferable to use alower setting.

It is to be noted that consumer devices may be preprogrammed withautomatically operating safety controls that inhibit the user frominadvertently exposing himself or herself to dangerous quantities oflight energy. Thus, in a relatively complex consumer product, the user'ssetting of one parameter at a potentially dangerous value will cause thedevice either to limit the selectable ranges of one or more other pulseparameters or to automatically adjust pulse parameters to prevent anexcessive rate of energy delivery. For instance, the selection of asmall inter-pulse interval (with a fixed total energy value) may preventthe user from selecting a short pulse duration and/or a small number ofpulses (that would result in a high intensity) or, alternatively, mayresult in an automatic diminution of the intensity (e.g., via engagementof an intensity-reducing filter).

A device for skin treatment comprises, in accordance with a feature ofthe present invention, a hand-holdable casing, a light generator mountedto said casing, and an applicator mounted to the casing for applyinglight from the generator to the skin surface. The applicator includes aflexible member at least partially conformable to the topography of theskin surface. The flexible member may take the form of a fluid-filledpouch or a piece of resilient plastic material. In either event, theapplicator is at least partially transparent to the light produced bythe generator for application to the skin surface.

The hand-held light treatment device may incorporate a generator ofultrasonic vibrations and/or an electromagnet for enabling theapplication of ultrasound energy or a magnetic field (preferablyoscillating) to a skin surface before, during or after the applicationof light energy. In the case of ultrasound energy, one or morepiezoelectric crystals are disposed in contact with the applicatorinterface, e.g., a flexible fluid-filled pouch. A wave generatortransmits an ultrasonic-frequency electrical signal to the piezoelectriccrystal(s) for producing ultrasonic vibrations in skin tissues.

Pursuant to another feature of the present invention, a marker film isapplied to a light-treated skin surface to indicate that electromagneticradiation has been applied to the skin surface. The marker film mayinclude a visually detectable pigment, for instance, zinc oxide,titanium dioxide, or a tinted transparent wash or dye. Where multiplepasses are to be made to a skin surface, the first and other non-finalpasses may leave a transparent or partially transparent film, while thefinal pass deposits an opaque coating (e.g., zinc oxide or titaniumdioxide) that is reflective so as to protect the skin against furtherinadvertent light exposure. The initial film deposits may be partiallyreflective to provide some measure of protection against inadvertentoverexposure. Alternatively, the marker film may be a visuallyundetectable composition, exemplarily micronized or microfine zincoxide. In that case, the light application device is provided with asensor that detects the marker film and disables or blocks lightapplication to any skin surface already treated with an effective amountof light.

The marker film is preferably applied by the same device that generatesthe light and directs the light to a skin surface. In that case, thedevice is provided with a reservoir of the marker composition and anapplicator such as a roller, nozzle, or atomizer.

Where several passes of light application are to be made to the skinsurface, each may be marked by an indicator composition of a respectivetint or color. The marker compositions should be both biocompatible andwater soluble for easy removal.

A hair treatment device in accordance with another feature of thepresent invention the present invention comprises a hand-holdablecasing, a generator of electromagnetic radiation mounted to the casing,and at least one optical element mounted to the casing so as to directelectromagnetic radiation produced by the generator in a directionsubstantially parallel to a skin surface, to impinge on hair fibersprotruding from the skin surface. The optical element may take the formof a partially reflective and partially transmissive mirror.

A light treatment device comprises, in accordance with a further featureof the present invention, a hand-holdable casing, and an applicatorinterface attached to the casing, the interface including aliquid-filled chamber having a flexible skin-contacting surface orpanel. A generator of electromagnetic radiation is mounted to thecasing, while at least one optical element mounted to the casing directslight from the generator through the liquid in the chamber towards askin surface in contact with the flexible skin-contacting surface orpanel. Preferably, the flexible skin-contacting surface or panel istransparent to the light from the generator.

A light treatment method in accordance with an additional feature of thepresent invention comprises generating light of a selected spectralcomposition, dividing the light into at least two bundles of light raysof substantially mutually exclusive wavelength ranges, and directing atleast one of the bundles of light rays towards a skin surface.

Where the one bundle of light rays is directed into the skin surface,the other bundle may be directed substantially parallel to the skinsurface to impinge on hairs protruding from the skin surface. The onebundle may include wavelengths in a range below approximately 750 nm,while the other bundle includes wavelengths in a range aboveapproximately 750 nm. Goggles for wear during light treatment inaccordance with this feature of the invention may be provided withlenses substantially opaque to light rays of the infrared bundle (750 nmand above) and at most partially transparent to light rays of the otherbundle. For example, the goggles may be opaque to all visiblewavelengths except a narrow band of wavelengths that are not included inthe bundle of wavelengths below 750 nm. If the goggles are completelytransparent to this narrow wavelength band, the band is filtered out ofthe visible light bundle. An indicator light such as an LED may beprovided that emits light in the narrow band to provide a signal to theuser that dangerous radiation is being produced. Alternatively, thegoggles may be at most partially transparent to the narrow wavelengthband. In this case, the goggles transmit enough light of the narrow bandto enable visual detection but not enough to damage the eye.

A hair treatment method comprises, in accordance with yet anotherfeature of the present invention, generating light of a selectedspectral composition, applying a dye to hair along a skin surface, andthereafter directing the generated light towards the dyed hair along theskin surface. This method is of particular for the removal of hair thatis white or very light colored. Preferably, the dye is applied to aselected section of the individual hairs, at the skin surface or at apredetermined distance above the skin surface.

Pursuant to another feature of the present invention, a marker film isapplied to a light-treated skin surface to indicate that electromagneticradiation has been applied to the skin surface. The marker film mayinclude a visually detectable pigment, for instance, zinc oxide,titanium dioxide, or a tinted transparent wash or dye. Alternatively,the marker film may be a visually undetectable, exemplarily micronizedor microfine zinc oxide. In that case, the light application device isprovided with a sensor that detects the marker film and disables orblocks light application to any skin surface already treated with aneffective amount of light.

The marker film is preferably applied by the same device that generatesthe light and directs the light to a skin surface. In that case, thedevice is provided with a reservoir of the marker composition and anapplicator such as a roller, nozzle, or atomizer.

Where several passes of light application are to be made to the skinsurface, each may be marked by an indicator composition of a respectivetint or color. The marker compositions should be both biocompatible andwater soluble for easy removal.

A hair treatment device in accordance with another feature of thepresent invention the present invention comprises a hand-holdablecasing, a generator of electromagnetic radiation mounted to the casing,and at least one optical element mounted to the casing so as to directelectromagnetic radiation produced by the generator in a directionsubstantially parallel to a skin surface, to impinge on hair fibersprotruding from the skin surface. The optical element may take the formof a partially reflective and partially transmissive mirror.

A light treatment device comprises, in accordance with a further featureof the present invention, a hand-holdable casing, and an applicatorinterface attached to the casing, the interface including aliquid-filled chamber having a flexible skin-contacting surface orpanel. A generator of electromagnetic radiation is mounted to thecasing, while at least one optical element mounted to the casing directslight from the generator through the liquid in the chamber towards askin surface in contact with the flexible skin-contacting surface orpanel. Preferably, the flexible skin-contacting surface or panel istransparent to the light from the generator.

A light treatment method in accordance with an additional feature of thepresent invention comprises generating light of a selected spectralcomposition, dividing the light into at least two bundles of light raysof substantially mutually exclusive wavelength ranges, and directing atleast one of the bundles of light rays towards a skin surface.

Where the one bundle of light rays is directed into the skin surface,the other bundle may be directed substantially parallel to the skinsurface to impinge on hairs protruding from the skin surface. The onebundle may include (visible) wavelengths in a range below approximately750 nm, while the other bundle includes (infrared) wavelengths in arange above approximately 750 nm. Goggles for wear during lighttreatment in accordance with this feature of the invention may beprovided with lenses substantially opaque to light rays of the infraredbundle and at most partially transparent to a selected band of lightrays of the visible bundle, as discussed above.

A hair treatment method comprises, in accordance with yet anotherfeature of the present invention, generating light of a selectedspectral composition, applying a dye to hair along a skin surface, andthereafter directing the generated light towards the dyed hair along theskin surface. This method is of particular for the removal of hair thatis white or very light colored. It should be understood that the presentmethodology may be used in professional settings, in spas or salons, byprofessional cosmetic service providers. Higher energies may be used insuch settings. Licensed medical professionals in medical offices may useeven higher energies and more complex settings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a light-pulse generating device for use ina method in accordance with the present invention.

FIG. 2 is a block diagram of another light-pulse generating device foruse in a method in accordance with the present invention.

FIG. 3 is a schematic diagram of possible modifications to thelight-pulse generating device of FIG. 2.

FIG. 4 is a schematic diagram of possible additional or alternativemodifications to the light-pulse generating device of FIG. 2.

FIG. 5 is a schematic diagram showing optics that may be incorporatedinto a light treatment device in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As described herein, a method for treating skin as a prophylactic toXray or ultraviolet radiation damage includes the application, to a skinsurface, of electromagnetic energy in the visible and/or infraredportions of the electromagnetic spectrum. The applied energy isalternatively referred to herein as “electromagnetic radiation” or“light.” The skin surface is generally in a preclinical condition, thatis, there is either no Xray or ultraviolet radiation damage or it is soslight as to be undetectable upon visual inspection.

As depicted in FIG. 1, a device for generating light pulses forapplication to a skin surface in a skin treatment process includes amanually operable setting selector 10 connected at an output to a memory12 in turn connected at an output to a control unit 14. Memory 12 storespre-established combinations of light pulse parameters including pulsewidth or duration, inter-pulse interval or delay time, pulse number,light intensity, and total treatment energy. Control unit 14 may be amicroprocessor or a special logic circuit connected to a pulse generator16 for inducing the generator to produce a sequence of electricalcontrol pulses fed to a source 18 of incoherent light energy. Source 18produces light with a spectral distribution including wavelengthsbetween 400 nm and 1200 nm. Control unit 14 may be connected directly tosource 18 where the source incorporates means for varying pulseparameters pursuant to encoded instructions.

Light source 18 (as well as the entire light pulse applicator) may takeany known form such as those disclosed in U.S. Pat. Nos. 6,280,438 and5,885,273. Thus, light source 18 may be a Xenon flashlamp.

Light 20 generated by source 18 is directed through an array of opticalelements 22 that may include one or more reflectors, lenses, and filters(not separately shown). Where an adjustable filter is included, controlunit 14 may be connected to the filter for operatively modifying theaction thereof. For instance, in the case of an adjustable neutraldensity filter, control unit 14 may induce a change in the filterdensity to control the intensity, and therefore the power, of the lightapplied to a selected skin surface.

In the case of multiple wavelengths of light being produced, anadjustable filter may be included in the optical elements 22 and/or theapplicator interface 26. These filters can block undesired wavelengthsand allow desired wavelengths to pass. Low end filters that block loweror shorter wavelengths, high end filters that block higher or longerwavelengths or band pass filters that block some high or some low endwavelengths may be utilized.

Light 24 leaving the optical array 22 is delivered or applied to a skinsurface via an applicator or interface element 26 exemplarily taking theform of a crystal. U.S. Pat. Nos. 6,280,438 and 5,885,273 disclose kindsof applicators or interfaces utilizable in the device of FIG. 1 (or 2).Applicator or interface element 26 may function in part to cool the skinsurface prior to, during, and/or after a light application procedure.Cooling may be accomplished by using a crystal-type applicator orinterface 26, with or without a layer of gel, as described in U.S. Pat.Nos. 6,280,438 and 5,885,273.

The elements of FIG. 1 are encased in or mounted to a housing 28 of asize and configuration enabling the pulse generation device to be handheld and easily manipulated for purposes of optically treating differentskin surfaces of the individual user.

The device of FIG. 1 is preprogrammed to produce light pulses in any ofseveral settings, each setting being defined by a respective combinationof particular operational parameters including pulse duration,inter-pulse interval, pulse number, and intensity or total energy. Forinstance, the device may have a plurality of settings, for instance,high, medium, and low, which vary in the number of applied pulses (e.g.,3, 2, 1), the pulse duration (9 msec, 7 msec, 5 msec), the inter-pulseinterval (250 msec, 300 msec, 350 msec), and/or the total energy applied(35 J/cm², 20 J/cm², 10 J/cm²). Usually, it is preferable to use thelowest setting which accomplishes the desired result. Generally, darkskin is more effective at light absorption that light skin and should betreated with lower settings (e.g., less overall energy) than light skin.

Setting selector 10 has a plurality of discrete settings differentiatedat least on the basis of skin tone. Different skin settings may include,for instance, dark skin, medium-tone skin, and light skin, or black,coffee, brown, tan, cream, and white. Setting selector 10 may alsoinclude a separate group of exposure settings for users to identify thedegree of sun exposure they have or expect to have. Exposure settingsmay include, for example, singular, occasional, frequent, and constant.

Control unit 14 may be connected to an LCD or other readable display 29for communicating to the user a recommended treatment schedule orprogram in response to the entries made by the user via selector 10.Depending on the user input, the read-out on display 29 may indicatesuch schedules as twice daily, once a day, once every other day, weekly,once on each of 3 days before sun exposure, just before exposure to sun,immediately before and after exposure to sun. The operationalparameters, including pulse duration, inter-pulse interval, pulsenumber, and intensity or total energy, are selected by control unit 14to conform to the recommended treatment schedule.

A more advanced or complex device is illustrated in FIG. 2. This deviceincludes a housing 30 having manually actuatable input elements 32, 34,36, and 38, such as rotary knobs or a solid-state touch screen, whichenable a user to individually select multiple operating parameters.Input elements or selectors 32, 34, 36, and 38 are an inter-pulseinterval selector, a pulse number selector, a power or energy selector,and a pulse duration selection, respectively. Another selector (notshown) could be for intensity adjustment, while a further selector maybe provided for adjusting a light source 42 or a filter in opticalelements 48 and/or an applicator 52 for modifying the wavelength banddelivered to the target skin surface. Selectors 32, 34, 36, and 38 areoperatively tied to a control unit 40 such as a microprocessor orhard-wired log circuit. Control unit 40 regulates the operation of lightsource 42 such as a conventional flashlamp, either directly orindirectly via a pulse generator 44. Light 46 from source 42 istransmitted along a path through optical elements 48 optionallyincluding one or more reflectors, lenses, and filters (not separatelyshown). Light 50 at an output of the optical array 48 is applied to askin surface via applicator or interface element 52. Applicator orinterface element 52 may take the form of a crystal block, a flexibleplastic element, and/or a transparent or translucent pouch filled with atransparent or translucent fluid such as a gel or a liquid. In the caseof the flexible element or the fluid-filled pouch, applicator orinterface element 52 conforms at least partially to the changingtopography of the skin surface under treatment, thereby facilitating theretention of gel between the applicator or interface 52 and the skinsurface. This result decreases the likelihood of overexposed or burnedskin and generally provides a more uniform application of light with auniformity of cooling. Safety is enhanced, while the outcomes tosuccessive procedures become increasingly standardized.

Where applicator 52 (or 26) includes a gel-filled pouch, the pouch (52)may be provided with perforations on a skin-contacting surface forexuding the gel for cooling purposes. Alternatively, as shown in FIG. 2,the light pulse device may be provided with a fluid dispenser such as aspray nozzle 54 connected to a valve 56 downstream of a pressurizedcoolant reservoir 58. In response to an operation of a manual actuator60 or in response to signals from control unit 40, valve 56 enables aflow of coolant from reservoir 58 to nozzle 54 for application to aselected skin surface. In the event that applicator or interface element52 is a bag or pouch, reservoir 58 and valve 56 may be connected to theapplicator or interface element for supplying a gel or fluid coolantthereto.

In one embodiment of the device of FIG. 2, suitable for professional butnot home use, inter-pulse interval selector 32 provides for intervals ina range from 1 msec and 2 seconds, whereas pulse number selector 34 isenabled for pulse sequences of one to ten pulses. In addition, powerselector 36 permits treatment energies between 0.01 Joule per squarecentimeter of skin surface and 200 Joules per square centimeter, whilepulse duration selector 38 enables pulses of 1 msec to 2 seconds inlength. Total pulse sequence duration, from the beginning of the firstpulse to the termination of the final pulse, ranges from 1 msec to 38seconds. The various pulse sequence parameters may be selectable fromsets of discrete values or, alternatively, from continuous ranges.

In the device of FIG. 2, the various parameters are typically notcompletely independent inasmuch as the total energy selected willfunction as a constraint on the ranges available for the otherparameters, that is, the total energy selected will serve to regulate orcircumscribe the ranges available to the user for the other pulsesequence parameters. Where the device of FIG. 2 has no intensityadjustment capability, a selection of the total energy and the pulseduration may determine the number of pulses. Similarly, a selection ofthe total energy and the number of pulses may determine the pulseduration. If the intensity is an adjustable parameter, once the totalenergy has been chosen, the user will be able to select the magnitudesof two of the three parameters, pulse duration, intensity and number ofpulses. The inter-pulse interval is related to the rate at which radiantenergy is applied to a skin surface and may accordingly be subjected tosome programmed control. Longer pulse durations and/or delays willdeliver energy at a slower rate (total energy is distributed over longertime) and therefore be safer to use with higher energy levels.Preferably, the total energy is always a selectable parameter and isbest selected prior to the setting of the other parameters. However, thedevice of FIG. 2 may be preprogrammed to limit the rate at which radiantenergy is applied to a skin surface, which will force restrictions onthe user's ability to select pulse parameter values.

In an alternative embodiment of the device of FIG. 2, suitable for homeuse, inter-pulse interval selector 32 enables a selection of intervalsranging from 200 msec to 2 seconds, while power selector 36 enablestreatment energies between 1 J/cm² and 40 J/cm². Preferably, the pulseduration and the number of pulses available for selection are restrictedso as to prevent the user from delivering energy at too high a rate. Ifthe user selects a large pulse number, the pulse duration is necessarilyshort, whereas a small number of pulses forces a longer pulse durationin order to achieve the selected total energy. Delivering the sameenergy over long pulse periods is safer. It is preferable to use alargest possible total pulse duration, assuming that none of theindividual pulse durations are shorter than a critical threshold level.Pulse number selector 34 may therefore enable a selection of three toten pulses per pulse sequence, while pulse duration selector 38 enablesa selection of pulses lasting 1 msec to 10 msec. The various pulsesequence parameters may be selectable from sets of discrete values or,alternatively, from continuous ranges.

A person uses the device of FIG. 1 or 2 to apply pulses of light to askin surface for purposes of effectively preventing or repairing damagedone by ultraviolet light to the cells of the skin and/or below thesurface of the skin. The absorption of the light pulses by melanin andother chromophores in the user's epidermal, dermal and subdermal tissuesis believed in part to promote the production of chemicals that reducethe incidence of Xray or ultraviolet radiation damage and inhibit thegrowth of cancerous cells. In addition, the light energy may increaseskin temperature slightly, through absorption and/or light scattering,for purposes of advancing tissue regenerative processes.

As further illustrated in FIG. 2, the light pulse applicator of thatdrawing figure may include an additional selector 62 for enabling theuser to load a skin tone value and an expected sun exposure level intocontrol unit 40. Setting selector 62 may take the form of a knob, akeypad, or manual switch enabling the user to enter a skin tone valuefrom a plurality of possible values. The possible selections may bequalitative descriptions: black, coffee, brown, tan, cream, white, etc.Alternatively, the possible skin tone selections may be quantitativewhere the integer 1 corresponds to the whitest skin tone while thenumeral 10 represents the darkest possible skin tone.

Setting selector 62 may also include a separate group of exposuresettings for users to identify the degree of sun exposure they have orexpect to have. Exposure settings may include qualitative descriptors:singular, occasional, frequent, and constant. Alternatively, thepossible exposure level selections may be any rational number along acontinuum between 0 and 10, where the lower boundary represents no sunexposure and the higher limit corresponds to continuous sun exposure.

Other possible input into control unit 40 via selector 62 may encode theclimate and season. For this parameter, a low value such as 0 mightrepresent winter in a polar region while 10 or 100 represents summer inan equatorial region.

Control unit 40 may be connected to an LCD or other readable display 64for prompting the user as to information to be input via selectors 32,34, 36, 38 and 62 and for communicating to the user a recommendedtreatment schedule or program in response to the entries made by theuser via selector 62. Control unit 40 may also use display 64 to alertthe user as to impermissible parameter combinations. Depending on theskin tone and sun exposure input received via selector 62, control unit40 may reject certain light parameter selections made by the user. Thereason for rejecting the user's selection of light pulse parameters maybe communicated to the user via display 64. Ranges of permissible valuesmay be displayed to facilitate the user's selection. The permissibleranges for outstanding parameters will vary depending on the user'sprior selections as discussed above.

In response to user input of skin tone and sun exposure levels, controlunit 40 may indicate on display 29 a plurality of possible lighttreatment schedules. The user may actuate selector 62 to choose apreferred treatment schedule. This choice is preferably made prior tothe selection of one or more light pulse parameters via selectors 32,34, 36, and 38. The available ranges of the remaining parameters will belimited in accordance with the user's selection of treatment schedule.

Generally, light treatment schedules are determined automatically inaccordance with a user's input to the light treatment device. To theextent that the user is allowed leeway in selecting individual pulseparameters, the device may impose limitations in accordance with theselected skin tone and sun exposure characteristics, as well as one ormore pulse parameters initially selected by the user.

The devices of FIGS. 1 and 2 may be used alternatively in the temporaryremoval of hair and/or the retardation of hair growth. The lighttreatment may be undertaken as an “after-shave” after the visible orprotruding hair has been removed by a conventional process such as byrazor or shaver.

The devices of FIGS. 1 and 2 are optionally provided with photocells andlight-emitting LEDs (none illustrated) for purposes of measuring skintone. The light pulses parameters may then be automatically selected inaccordance with the measured skin tone. The LEDs and photocells areconnected to the respective control unit 14, 40 for taking measurementsin response to signals from that unit.

In another optional modification, the devices of FIGS. 1 and 2 may beprovided with infrared sensors (not shown) for generally sensing adegree of sun exposure. This option is useful principally forlight-pulse application immediately after sun exposure. The infraredsensor is operatively connected to the respective control unit 14, 40 toinform unit's selection of pulse parameters. Where there is a markeddegree of sun exposure (resulting in a high skin temperature and agreater-than-usual emission of infrared radiation), control unit 14, 40may select pulse parameters for a maximum possible energy application.For a single session, the treatment may have the longest possibleduration (30-40 seconds). Alternatively, particularly with the device ofFIG. 2, control unit 40 may recommend to the user a series of treatmentsessions spread out over several days.

In yet another optional modification, the user of a skin treatmentdevice as described with reference to FIG. 1 or 2 may be provided with aUV sensor (not illustrated) for sensing the degree of sun exposure. Ifthe sensor is on the light treatment device, the sensor may be connectedto control unit 14, 40. The sensor and the control unit 14, 40 maycooperate to measure a total amount of UV exposure. The control unit isprogrammed to select light treatment parameters and possibly a treatmentschedule in accordance with the detected instantaneous or cumulativeamount of UV radiation. The light treatment may be during or after theUV exposure.

As depicted in FIG. 3, the light treatment devices of FIGS. 1 and 2 mayincorporate a generator 66 of ultrasonic vibrations and/or anelectromagnet 68 for enabling the application of ultrasound energy or amagnetic field (preferably oscillating) to a skin surface before, duringor after the application of light energy. Permissible and recommendedvariations in the relevant parameters are well known in the skintreatment arts. In the case of ultrasound energy, one or morepiezoelectric crystals 70 are disposed in or in contact with anapplicator interface 72, e.g., a fluid-filled member having a flexiblepanel 74 for contacting and conforming to the skin surface. A waveformgenerator 76 transmits an ultrasonic-frequency electrical signal to thepiezoelectric crystal(s) 70 for producing ultrasonic vibrations in skintissues. An AC voltage generator 78 is operatively connected to anelectromagnetic coil 80 for generating an alternating magnetic field inthe skin tissues.

The applicator interface 72 of FIG. 3 includes an enlarged contactmember or head 82 connected to the housing 28, 30 by a stem 84. Head 82and optionally stem 84 are filled with a coolant fluid such as water ora gel. Prior to the use of the light-generating instrument, head 82 andoptionally stem 84 may be stored in a refrigeration unit for purposes ofreducing the temperature the water or gel. In that event, head 82 orstem 84 is provided with a connector (not shown) for detachably couplingthe head or the stem to housing 28, 30. The connector includeselectrical contacts (not shown) for the transmission of ultrasonicelectrical waves from frequency generator 76 and another signal from ACvoltage generator 78. In an alternative, more expensive embodiment of alight generating apparatus, the fluid in interface 72 may be circulatedfrom a heat exchange unit (not shown) by a pump (not shown).

Applicator interface 72 has an opaque outer surface (not separatelydesignated) except along an area 86 of skin-contacting panel 74 oppositestem 84. Light 50 at an output of the optical array 48 is transmittedthrough stem 84, head 82, and transparent area 86.

As illustrated in FIG. 3, piezoelectric crystals 70 and coil 80 may bedisposed inside head 82. Where the fluid is electrically conductive,crystals 70 and coil 80 are provided with appropriate electricalinsulation such as a coating of a thermoplastic resin material.Alternatively, crystals 70 and coil 80 may be disposed inside housing 28or 30. In that case, crystals 70 are in mechanical contact with stem 84so as to enable the transmission of ultrasonic pressure waves throughstem 84 and head 82 to panel 74. Electromagnetic coil 80 is of such assize that the magnetic field generated inside the dermal tissues issufficiently large to effectively treat the skin tissues, in conjunctionwith the light treatment and optionally ultrasound.

As depicted in FIG. 3, head 82 is further provided with optics (e.g., apartially silvered mirror 88) for transmitting light 90 in a directionparallel to a skin surface. The light exits head 82 at a window 92provided along a leading edge of the head for purposes of applying thelight to hair protruding from the skin surface. The light 90 singes thehair which is then broken off by a bumper element 94 protruding slightlyfrom a lower surface of panel 74. The removal of the hair enhances theeffectiveness of the light penetration into the dermal tissues. A shield96 may extend from the leading end of head 82 to block the escape oflight 90 from a hair-treatment space immediately in advance of window92.

Mirror 88 is tilted at an approximately 45° angle to the direction oftransmission of light 50, i.e., at an approximately 45° angle to aperpendicular or normal to the skin surface. In a variation on the hairremoval feature implemented via mirror 88, the mirror is tilted at a 90°angle to the orientation shown in FIG. 3, for reflecting, in thedirection of transmission of light 90 (generally parallel to the skinsurface), that portion of light beam 50 that has been reflected from thetarget skin surface. Thus, reflected light is used to shave hair, thesinging and breaking of the hairs occurring generally at the point ofemergence thereof from the skin surface. This embodiment of the deviceof FIG. 3 tends to conserve energy relative to the illustratedembodiment. Thus, the light treatment device can be made with a lesspowerful light source, reducing the cost of the device.

The embodiment of FIG. 3 may be modified to produce a light treatmentdevice solely for hair removal at the skin surface alone. In that case,mirror 88 may be completely reflective so as to direct all the light of“vertical” beam 50 to form “horizontal” beam 90.

As depicted in FIG. 4, the light treatment devices of FIGS. 1, 2 and 3may incorporate a reservoir 102 of a composition to be applied as amarker film to a light-treated skin surface to indicate thatelectromagnetic radiation has been applied to the skin surface. Themarker film composition in reservoir 102 may include a visuallydetectable pigment, for instance, zinc oxide, titanium dioxide, or atinted transparent wash or dye. Where multiple passes are to be made toa skin surface, the first and other non-final passes may leave atransparent or partially transparent film, while the final pass depositsan opaque coating (e.g., zinc oxide or titanium dioxide) that isreflective so as to protect the skin against further inadvertent lightexposure. The initial film deposits may be partially reflective toprovide some measure of protection against inadvertent overexposure.Alternatively, the marker film composition in reservoir 102 may be avisually undetectable substance, such as micronized or microfine zincoxide. In any case, the marker composition(s) in reservoir 102 arepreferably both biocompatible and water soluble for easy removal.

As further depicted in FIG. 4, the light treatment devices of FIGS. 1, 2and 3 may also incorporate an applicator 104 communicating withreservoir 102 and disposable in proximity to a skin surface applyingmetered amounts of the marker film composition to the skin surface uponan administration of light to the skin surface pursuant to thedisclosure hereinabove. Applicator 104 exemplarily takes the form of aroller, a brush, a nozzle, or an atomizer.

Where the marker film composition in reservoir 102 is a visuallyundetectable substance, the light application device is provided with asensor 106 that detects whether the marker film composition is presenton a skin surface. In the event sensor 106 detects the presence of themarker film composition, the sensor disables or blocks light applicationto the respective skin surface. Sensor 106 may be connected tomicroprocessor or control unit 14 or 40 for inducing that unit tointerrupt, or terminate the generation of light by generator 16, 44, or66.

Where a light treatment procedure involves several passes along a targetskin surface, each pass may be marked by an indicator composition of arespective tint or color. In that case, reservoir 102 includes aplurality of sub-reservoirs each containing a composition of arespective tint or color. A button, knob or other input element 108 maybe operatively connected to the microprocessor or control unit 14 or 40for selecting the color or tint of the marker film composition to beapplied to the skin. Microprocessor or control unit 14, 40 may implementthe color or tint selection by operating a valve 110 disposed betweenreservoir 102 and applicator 104.

Where the marker film composition in reservoir 102 includes a dye thatis absorbed into hair, the applicator 104 may be used to apply a dye tolight colored or white hair prior to an application of light to thehair. The dye is applied to the hair along a selected skin surface, andthereafter light is directed towards the dyed hair. This method is ofparticular for the removal of hair that is white or very light colored.A button or other input element (not shown) may be provided fordisabling the light application during the application of the dye to thehair.

As shown in FIG. 5, optical elements 22 or 48 of the light treatmentdevices of FIGS. 1, 2 and 3 may incorporate a primary prism 112, twomirrored surfaces 114 and 116, and a pair of secondary prisms 118 and120 for splitting light from source 18 or 42 into at least two bundles122 and 124 of light rays of substantially mutually exclusive wavelengthranges. At least one of the bundles of light rays 122 is directedtowards a skin surface. The other bundle 124 may be directedsubstantially parallel to the skin surface to impinge on hairsprotruding from the skin surface, as discussed above with reference toFIG. 3. Bundles 122 and 124 each typically include visible wavelengths.

The user of the light treatment device of FIG. 5 may be provided withgoggles (not shown) having lenses that are substantially opaque to lightrays of bundle 122 and at most only partially transparent to a selectedband of light rays of bundle 124. The goggles are effectively opaque towavelengths outside of the selected band. If the goggles are completelytransparent to this narrow wavelength band, the band is filtered out ofbundle 124. An indicator light such as an LED (not shown) may beprovided that emits light in the narrow band to provide a signal to theuser that dangerous radiation is being produced. Alternatively, thegoggles may be at most partially transparent to the narrow wavelengthband. In this case, the goggles transmit enough light of the narrow bandto enable visual detection but not enough to damage the eye.

It is possible to generate a “vertical” bundle of essentially onlyvisible wavelengths (shorter than about 750 nm) and a “horizontal”bundle of only infrared wavelengths (longer than about 750 nm). Thiskind of wavelength distribution over the bundles may be implemented byhaving separate radiation generators and at least partially separatetransmission paths. Alternatively, if a single generator produces bothvisible and infrared radiation, optics may be provided for splitting outthe visible wavelengths from the infrared wavelengths.

In determining optimal settings with the device of FIG. 2, a user shouldchoose initial parameter values which in combination result in theapplication of small amounts of energy. Thus, where one or more selectedpulse parameters tend to produce higher treatment energies, other pulseparameters should be selected that that tend to produce lower treatmentenergies.

Where all the pulse parameters are independently adjustable, lowertreatment energies will generally result from settings involving fewpulses (say, 1-3 instead of 8-10 pulses), long inter-pulse intervals(300 msec or more), short pulse durations (20 msec or less), low lightintensity (if selectable, for example, via an adjustable neutral densityfilter), and low total energies (less than 40 Joules per squarecentimeter of skin surface). If a given setting proves to be ineffectivein improving skin appearance after sun exposure, the user might adjustselector 32 or 38 to decrease the inter-pulse interval or decrease thepulse length, thereby effectively increasing the power or rate at whichthe radiant energy is delivered to the target skin surface.Alternatively or additionally, the user might increase the number ofpulses via selector 34 or increase the applied energy via selector 36.These adjustments will result in an increase in the rate of appliedenergy if the total time of the pulse sequence is limited. If the lightintensity is separately adjustable, one may increase the power or rateof energy delivery by simply selecting a higher intensity value.

Where the various pulse parameters are not independently selectable, forinstance, where the total energy applied is a controlling factor,adjustments made in the parameters for purposes of incrementallyenhancing the skin treatment effectiveness of the device of FIG. 2 willbe different from the case of completely independent parameter values.For instance, once the total applied energy and total pulse sequencetime have been selected, decreasing the number of pulses will require anincrease in pulse length and/or an increase in pulse intensity in orderto deliver the same amount of total energy in the fixed time. Thesechanges will increase the effectiveness of the light applicationinasmuch as the rate of energy delivery is increased. In contrast, oncethe total applied energy and total pulse sequence time have beenselected, increasing the pulse duration will decrease the instantaneousrate at which energy is applied to the target skin surface by decreasingthe light intensity.

Because different skin areas have different skin pigmentation, differentvascularization, etc., different pulse parameter settings arerecommended for different skin areas. For example, different settingswill be necessary for the lower surfaces of the arms, the backs of theknees, and the upper surfaces of the feet in order to optimize results.

The present skin treatment method contemplates the application to aselected skin surface of a pulse sequence having a predetermined numberof pulses of light of a predetermined electromagnetic spectrum, apredetermined duration, a predetermined inter-pulse interval, and apredetermined total energy. These pulse sequence parameters aredetermined in part by the design of the light-generating device used andin part by the selections as to skin tone and, optionally, sun exposurelevel made by the user.

The light of the pulses is generally incoherent and the spectrumincludes wavelengths between about 400 nm and 1200 nm. However, singlewavelengths of laser or coherent light may be delivered at one time,when desired. Higher wavelengths are used for darker skin and/or fordeeper penetration into dermal tissues.

The light applied to a skin surface by the devices of FIGS. 1 and 2includes at least one wavelength absorbable by an endogenous chromophorein a person's skin. The endogenous chromophore may be a form of melanin.Alternatively or additionally, the endogenous chromophore is hemoglobin.In a more advanced embodiment the light application device may include asetting or control (not shown) for selecting a spectrum or range ofwavelengths appropriate to the user's skin color. In any event, thedevices of FIGS. 1 and 2 are generally used without the application ofan exogenous chromophore to a target skin surface for light absorptionpurposes. However, it is possible for an individual to apply anexogenous chromophore such as porphyrin that is absorbed by the skincells. Of course, the user should vary the light treatment to accordwith the resulting light absorption.

In other embodiments of a light generation and application device forhair treatment, one or more of the pulse parameters may vary during asingle treatment session. For instance, the inter-pulse interval or thepulse duration may increase or decrease from the beginning of a pulsesequence to the end of the pulse sequence. The resulting instantaneousrate of energy application may therefore vary during the pulse sequence.

Listed below are a number of exemplary settings or combinations ofoperational parameters particularly suitable for home-use and attainablewith either the device of FIG. 1 having pre-established settings orparameter combinations or the device of FIG. 2 where the various pulsesequence parameters may be individually adjusted independently of theother parameters. In these examples, the total times of the pulsesequences are determined by the selected numbers of pulses, the selectedpulse durations and the selected inter-pulse intervals. The lightintensity may be automatically adjusted by the light generating deviceif necessary to ensure consistency among the listed parameter settings.

Home Use Example 1. In a preferred setting or combination of operationalparameters suitable for home use, an incoherent light applicator devicefor skin treatment generates pulses with a pulse number of two, a pulseduration of 7 msec, an inter-pulse interval of 300 msec, a total pulseenergy of 20 J/cm², and a spectral distribution of a commerciallyavailable flashlamp, including wavelengths between 500 and 1200 nm.

Home Use Example 2. A slightly higher setting or combination ofoperational parameters for an incoherent light applicator devicesuitable for home use involves a pulse sequence with a pulse number oftwo, a pulse duration of 7 msec, an inter-pulse interval of 250 msec, atotal pulse energy of 20 J/cm², and a spectral distribution of acommercially available flashlamp, including wavelengths between 500 and1200 nm. Although the total amount of energy is the same as in the firstexample, the shorter interpulse interval means that the rate of energytransmission to the target skin surface is higher.

Home Use Example 3. A higher setting or combination of operationalparameters for an incoherent light applicator device involves pulseswith a pulse number of two, a pulse duration of 5 msec, an inter-pulseinterval of 250 msec, a total pulse energy of 25 J/cm², and a spectraldistribution of a commercially available flashlamp, includingwavelengths between 500 and 1200 nm. In this example, not only is thetotal energy larger than in the second example, but the rate of energyapplication is higher owing to the shorter pulse duration.

Home Use Example 4. An even higher setting or combination of operationalparameters for an incoherent light applicator device involves pulseswith a pulse number of two, a pulse duration of 5 msec, an inter-pulseinterval of 210 msec, a total pulse energy of 37 J/cm², and a spectraldistribution of a commercially available flashlamp, includingwavelengths between 500 and 1200 nm. The pulse sequence of this exampledelivers radiant energy at a higher rate than in the third examplebecause of the shorter inter-pulse interval and the slightly higherenergy delivered per pulse.

Home Use Example 5. In a low setting or combination of operationalparameters, an incoherent light applicator device produces pulses with apulse number of two, a pulse duration of 5 msec, an inter-pulse intervalof 350 msec, a total pulse energy of 15 J/cm², and a spectraldistribution of a commercially available flashlamp, includingwavelengths between 500 and 1200 nm. The pulse sequence of this exampledelivers a small amount of energy, at a low rate (e.g., long inter-pulseinterval).

Home Use Example 6. A slightly higher setting or combination ofoperational parameters for an incoherent light applicator deviceinvolves pulses with a pulse number of two, a pulse duration of 5 msec,an inter-pulse interval of 300 msec, a total pulse energy of 20 J/cm²,and a spectral distribution of a commercially available flashlamp,including wavelengths between 500 and 1200 nm.

Home Use Example 7. A lower setting or combination of operationalparameters for an incoherent light applicator device involves pulseswith a pulse number of three, a pulse duration of 5 msec, an inter-pulseinterval of 300 msec, a total pulse energy of 20 J/cm², and a spectraldistribution of a commercially available flashlamp, includingwavelengths between 500 and 1200 nm.

Home Use Example 8. Another setting or combination of operationalparameters for an incoherent light applicator device involves pulseswith a pulse number of two, a pulse duration of 7 msec, an inter-pulseinterval of 250 msec, a total pulse energy of 20 J/cm², and a spectraldistribution of a commercially available flashlamp, includingwavelengths between 500 and 1200 nm.

The devices of FIGS. 1 and 2 may be provided with a band-pass filter forlimiting the spectral distribution of the generated light pulses towavelengths in a given band, for instance, between 700 nm and 900 nm.Alternatively, a low-pass filter may be used for transmitting to a skinsurface only wavelengths less than a predetermined maximum, such as 900nm, 750 nm, or 550 nm. The lower the wavelength the less likely thelight will penetrate deeply and damage cellular and histologicalelements as deep as the bulb parts of the hair follicles. Shorterwavelengths, for instance, below 550 nm are useful for limiting thedepth of penetration.

Depth of penetration may also be limited by using lower lightintensities. Neutral density or “gray” filters may be used to reduce theintensity of the light applied to the selected skin surfaces.

Listed below are a number of exemplary settings or combinations ofoperational parameters particularly suitable for professional devices.In these examples, the selected numbers of pulses, the selected pulsedurations and the selected inter-pulse intervals determine the totaltimes of the pulse sequences. The light-generating device, if necessaryto ensure consistency among the listed parameter settings, mayautomatically adjust the light intensity.

Professional Use Example 1. In a setting or combination of operationalparameters suitable for professional use, an incoherent light applicatordevice for skin treatment generates pulses with a pulse number of two, apulse duration of 7 msec, an inter-pulse interval of 150 msec, a totalpulse energy of 60 J/cm², and a spectral distribution of a commerciallyavailable flashlamp, including wavelengths between 500 and 1200 nm.

Professional Use Example 2. A slightly higher setting or combination ofoperational parameters for an incoherent light applicator deviceinvolves pulses with a pulse number of two, a pulse duration of 7 msec,an inter-pulse interval of 100 msec, a total pulse energy of 60 J/cm²,and a spectral distribution of a commercially available flashlamp,including wavelengths between 500 and 1200 nm.

Professional Use Example 3. A lower setting or combination ofoperational parameters for an incoherent light applicator deviceinvolves pulses with a pulse number of two, a pulse duration of 9 msec,an inter-pulse interval of 100 msec, a total pulse energy of 60 J/cm²,and a spectral distribution of a commercially available flashlamp,including wavelengths between 500 and 1200 nm.

Professional Use Example 4. A higher setting or combination ofoperational parameters for an incoherent light applicator deviceinvolves pulses with a pulse number of two, a pulse duration of 9 msec,an inter-pulse interval of 100 msec, a total pulse energy of 100 J/cm²,and a spectral distribution of a commercially available flashlamp,including wavelengths between 500 and 1200 nm.

Professional Use Example 5. In a relatively low setting or combinationof operational parameters for professional use, an incoherent lightapplicator device produces pulses with a pulse number of two, a pulseduration of 9 msec, an inter-pulse interval of 200 msec, a total pulseenergy of 40 J/cm², and a spectral distribution of a commerciallyavailable flashlamp, including wavelengths between 500 and 1200 nm.

Professional Use Example 6. A slightly higher setting or combination ofoperational parameters for an incoherent light applicator deviceinvolves pulses with a pulse number of two, a pulse duration of 5 msec,an inter-pulse interval of 150 msec, a total pulse energy of 40 J/cm²,and a spectral distribution of a commercially available flashlamp,including wavelengths between 500 and 1200 nm.

Professional Use Example 7. Another higher setting or combination ofoperational parameters for an incoherent light applicator deviceinvolves pulses with a pulse number of two, a pulse duration of 5 msec,an inter-pulse interval of 150 msec, a total pulse energy of 50 J/cm²,and a spectral distribution of a commercially available flashlamp,including wavelengths between 500 and 1200 nm.

Professional Use Example 8. A further combination of operationalparameters for an incoherent light applicator device involves pulseswith a pulse number of two, a pulse duration of about 5.8 msec, aninterpulse interval of approximately 20 msec, and a total applied energyof between about 20 Joules per square centimeter of said skin surfaceand about 90 Joules per square centimeter of said skin surface.

Professional Use Example 9. Yet another setting or combination ofoperational parameters for an incoherent light applicator deviceinvolves pulses with a pulse number of one a pulse duration of betweenabout 18 msec and 25 msec, and a total applied energy of between about20 Joules per square centimeter of said skin surface and about 90 Joulesper square centimeter of said skin surface.

An incoherent light applicator device for professional use may also beprovided with a band-pass filter for limiting the spectral distributionof the generated light pulses to wavelengths in a given band, forinstance, between 700 nm and 900 nm. Again, a low-pass filter may beused for transmitting to a skin surface only wavelengths less than apredetermined maximum, such as 900 nm, 750 nm, or 550 nm.

In the skin treatment method described above with reference to FIGS. 1and 2, visible and/or infrared light energy is applied to a skin surfacefor absorption by melanin in the epidermis and hemoglobin in thecapillaries and blood vessels of the dermis. The absorption of light(visible and/or infrared) increases the local temperature in the tissuescontaining the chromophores, particularly the blood vessel cell wallsand keratinocytes in the skin. The rise in heat of these structures, andothers such as collagen and Langerhans cells, may release factors thatstimulate collagen synthesis and/or remodeling.

It is to be noted that the skin treatment method described herein allowsfor multiple passes over any particular skin surface. The selected lighttreatment parameters may be the same for each pass or may vary from passto pass. In addition, the passes may follow immediately after oneanother or may be spaced by an interval during which, for instance, thelight treatment device is used to apply light pulses to another area ofthe user's skin. An advantage of multiple passes is that the total powerapplied to a given skin surface may be reduced relative to that neededfor accomplishing the desired prophylactic treatment by a single pass.For example, instead of a single pass of 50 Joules/cm², skin could beeffectively treated by two passes of 20 Joules/cm² apiece. If the numberof passes is increased further, the total power may be reduced evenmore. For instance, twenty passes may require a power no greater than0.01 Joule/cm². Multiple passes can be used to treat tanned skin withoutany undesirable effects. Thus, it is safer to use multiple passes than asingle pass. Also, it is more efficient to use multiple passes ratherthan a single pass. Light application devices for multiple-passtreatments are less expensive and easier to build that devices forsingle-pass treatments. A scanner may be provided for rapidlyimplementing a high number of passes without undue exertion by theoperator. Where a skin treatment session comprises multiple passes overany particular area of skin, each pass is constituted by one or morelight pulses. Where each pass includes multiple pulses in a respectivepulse packet, the pulse packets are separated by a period that is greatin comparison to the interpulse duration(s) of the pulse packets. Thisinter-packet period may be anywhere from one-tenth of a second to ten ortwenty minutes. Where a hand treatment device as disclosed above withreference to FIGS. 1 and 2 is being used, it is convenient to treat anentire skin surface with a first pulse packet during a first pass andthen treat the same skin surface with a second pulse packet during asecond pass. Where a light chamber or box is used, the individual neednot wait for longer than a few seconds between successive pulse packets,thereby obviating any fatigue or boredom. A prophylactic light treatmentas described hereinabove is useful to counteract the deleterious effectsof tanning salons as well as of sun exposure, for example, at a beach orswimming pool. In these cases, it is advantageous to the customers ofthe tanning salon or the users of the beach or pool to provide a lightchamber or box where the customers and users may be subjected to a lighttreatment over large areas of the skin simultaneously. The same chamberthat is used for the tanning treatment may be used for prophylacticlight treatment. In that case, the visible and/or infrared radiationemitters (bulbs) may be disposed in place of, or in addition to, thetanning radiation sources. The user preferably wears goggles to protectthe eyes and may stand or sit in a small enclosure (light chamber orbox, not shown) while light energy with appropriate parameters isapplied to the entire exposed skin surface. In a light chamber, lightmay be applied via a contact device, as described specificallyhereinabove with reference to FIGS. 1-3, or via a non-contact apparatus,as where the walls of the chamber are provided with diffuse lightsources that bathe the individual uniformly in light energy. It ispossible also for the light application to be effectuated in aliquid-containing enclosure such as a pool, where a liquid such as anaqueous solution serves in part to conduct light to the skin surfaces ofthe individual user and to remove excess heat generated in the skintissues by the absorption or scattering of the light. It is noted inaddition that water is a more efficient medium for light transmissionthan is air. Light may be conveyed to the individual's skin in part viaa crystal or pouch-type applicator, as discussed above with reference toFIGS. 1-3, in part via liquid in a pool in which at least a portion ofthe individual is situated, and/or in part via the ambient air in alight chamber or box, as discussed above.

Although the invention has been described in terms of particularembodiments and applications, one of ordinary skill in the art, in lightof this teaching, can generate additional embodiments and modificationswithout departing from the spirit of or exceeding the scope of theclaimed invention. For example, light sources 18 and 42 may take theform of laser sources. In that case, if optical elements 22 and 48include any filters, those filters are neutral density filters forreducing the intensity of the transmitted radiation. Where light sources18 and 42 are tunable laser sources, then an additional actuator may beprovided for frequency selection purposes. Accordingly, it is to beunderstood that the drawings and descriptions herein are proffered byway of example to facilitate comprehension of the invention and shouldnot be construed to limit the scope thereof.

1. A skin injury or damage prevention method for at least reducing theincidence or likelihood of non-cancerous visible damage to the skinincluding radiation dermatitis, sunburns, and poikiloderma, said methodcomprising periodically applying, in temporally spaced treatmentsessions, pulses of electromagnetic radiation to a skin surface of anindividual in the absence of an applied exogenous chromophore and in theabsence of visible radiation damage on said skin surface, the applyingof said pulses including selecting pulse parameters including pulseduration and total energy so as to at least reduce the incidence orlikelihood of non-cancerous visible damage to the skin includingradiation dermatitis, sunburns, and poikiloderma caused by exposure ofthe individual to skin-damaging radiation, the applying of saidelectromagnetic radiation to said skin surface in each of said treatmentsessions being effectuated within a predetermined interval of theexposure of the individual to skin-damaging radiation, therebyeffectively preventing skin injury or damage by reducing the incidenceor likelihood of non-cancerous visible damage to the skin includingradiation dermatitis, sunburns, and poikiloderma, the applying of saidelectromagnetic radiation to said skin surface increasing the localtemperature in skin structures including blood vessel cell walls andkeratinocytes in the skin to stimulate a healing response and a releaseof growth factors and other tissue substances, without permanentlydamaging any skin structures, said pulses of electromagnetic radiationbeing characterized by parameters including pulse duration of less thanabout 2 seconds, wavelength and total energy so selected that theapplying of said electromagnetic radiation promotes healthy skin andgenerates no visible damage such as tanning, wherein the number of saidtreatment sessions in a given time interval is determined at least inpart by the frequency or intensity of exposure to skin-damagingradiation during that time interval.
 2. The method defined in claim 1wherein said pulses of electromagnetic radiation each have wavelengthsbetween 400 nm and 1200 nm only.
 3. The method defined in claim 1wherein said predetermined interval is less than one week.
 4. The methoddefined in claim 1 wherein said predetermined interval is less thanthree days.
 5. The method defined in claim 1 wherein said predeterminedinterval is less than one day.
 6. The method defined in claim 1 whereinsaid skin surface is not directly exposed to a source of skin-damagingradiation.
 7. A skin injury or damage prevention method for at leastreducing the incidence or likelihood of non-cancerous visible damage tothe skin including radiation dermatitis, sunburns, and poikiloderma,said method comprising applying energy, in temporally spaced treatmentsessions, to a skin surface of an individual in the absence of visibleradiation damage on said skin surface, the applied energy being takenfrom the group consisting of mechanical waveform energy and magneticfield energy, the applied energy being selected so as to at least reducethe incidence or likelihood of non-cancerous visible damage to the skinincluding radiation dermatitis, sunburns, and poikiloderma caused byexposure of the individual to skin-damaging radiation, the applying ofsaid energy to said skin surface in each of said treatment sessionsbeing effectuated within a predetermined interval of the exposure of theindividual to skin-damaging radiation, thereby effectively preventingskin injury or damage by reducing the incidence or likelihood ofnon-cancerous visible damage to the skin including radiation dermatitis,sunburns, and poikiloderma, wherein the number of said treatmentsessions in a given time interval is determined at least in part by thefrequency or intensity of exposure to skin-damaging radiation duringthat time interval.
 8. A skin injury or damage prevention method for atleast reducing the incidence or likelihood of non-cancerous visibledamage to the skin including radiation dermatitis, sunburns, andpoikiloderma, said method comprising periodically applying, intemporally spaced treatment sessions, electromagnetic radiation to askin surface of an individual in the absence of visible skin-damagingradiation damage on said skin surface, the applying of saidelectromagnetic radiation including selecting pulse parameters includingpulse duration and total energy so as to at least reduce the incidenceor likelihood of non-cancerous visible damage to the skin includingradiation dermatitis, sunburns, and poikiloderma caused by exposure ofthe individual to skin-damaging radiation, the applying of saidelectromagnetic radiation to said skin surface in each of said treatmentsessions being effectuated during or after the exposure of theindividual to skin-damaging radiation, within a predetermined intervalof such exposure, thereby effectively preventing skin injury or damageby reducing the incidence or likelihood of non-cancerous visible damageto the skin including radiation dermatitis, sunburns, and poikiloderma,said electromagnetic radiation being characterized by parametersincluding pulse duration, wavelength and total energy so selected thatthe applying of said electromagnetic radiation promotes healthy skin andgenerates no visible damage such as tanning, wherein the number of saidtreatment sessions in a given time interval is determined at least inpart by the frequency or intensity of exposure to skin-damagingradiation during that time interval.